1. Field of the Invention
The present invention is directed to a wetlaid paper-like nonwoven structure having a permanent crepe which does not wash out. More particularly, the present invention is directed to a paper-like structure with a permanent crepe, for example, a wipe structure which possesses both wet and dry strength and improved absorbent properties. The present invention is also concerned with the method of manufacturing such paper-like structures.
2. Description of the Background Art
Crepe tissue products have a general utility in applications where absorbency is a factor. These include, for example, household and industrial wipes, towels, packaging, cushioning materials and the like.
In recent years, paper products made from wood pulp combined with various types of synthetic polymers have been investigated with the intention of imparting to paper products made from wood pulp, those advantageous properties which can be introduced by the presence of synthetic polymeric materials. Thus, for example, Japanese Publication No. 48-1443 (1973) discloses creping a web from a heated roller wherein the web contains at least 20 percent by weight of a thermoplastic synthetic fiber. Thus, raw paper containing at least 20 percent by weight of thermoplastic synthetic fiber is conveyed around a pair of heating rollers having a surface temperature which varies from the softening point of the synthetic fiber to about 30.degree. C. above its melting point. The raw paper, which is heated on the rollers, is continuously scraped off the surface of the roller by means of a fixed doctor knife, thereby forming crepe patterns on the paper. The paper is then conveyed around a cooling roller to heat-set the crepe pattern. This publication specifically indicates that if there is any deviation in the amount of thermoplastic synthetic fibers included in the raw paper, for example, if the percentage weight of the thermoplastic synthetic fiber in the raw paper is less than 20 percent, crepe paper of the type desired by the publication cannot be achieved.
U.S. Pat. No. 4,640,810 discloses in column 4, lines 41-47, the general advantages of providing a mixture of relatively long thermoplastic fibers and wood pulp fibers wherein the thermoplastic fibers are activated by the application of heat and/or pressure.
U.S. Pat. No. 4,204,054 discloses fibrous structures in sheet form having from 10 percent to 90 percent by weight of pulp of cellulosic fibers crosslinked with formaldehyde, and 90 percent to 10 percent by weight of an additional binding product, with the amount of the additional binding product being selected to insure sufficient strength and cohesion to the structure of the sheet. The additional binding product is a non-crosslinked fiber which, in one variation, can be a synthetic pulp, such as for example low density polyethylene fibers, present within the range of 10 to 40 percent and preferably about 15 percent.
U.S. Pat. No. 4,790,907 discloses in column 1, lines 53 to 62 that synthetic pulps, filaments and fibers are useful for the manufacture of paper articles and can be used with conventional papermaking equipment. Common synthetic materials used in the paper pulps include high density polyethylene or polypropylene, and aramids, for example, Kevlar and Nomex. Pulps prepared from other polymers are also known, for example, aliphatic polyamides, polyvinyl chloride, acrylonitrile homopolymers and copolymers with halogenated monomers, styrene copolymers and mixtures of polymers.
U.S. Pat. No. 4,645,566 discloses a process for producing an electroconductive film wherein a thermoplastic synthetic pulp is mixed with a thermoplastic composite fiber having as a first component a lower melting point than that of said thermoplastic synthetic pulp and a second component having a higher melting point than that of said thermoplastic synthetic pulp.
U.S. Pat. No. 4,655,877 discloses an absorbent web structure composed of short fibers of a thermoplastic resin which is rendered hydrophilic with a surface-active agent mixed with cellulosic fibers, said thermoplastic short fibers being melt-bonded to impart self-supporting properties to the web structure.
Finally, U.S. Pat. No. 3,846,228 discloses forming tissue paper by pressing the web while on an up-running forming wire and transferring the web directly to a Yankee Dryer where it is creped. There appears to be no indication that the paper utilized in this patent contains synthetic fibers.